In the rigging trade, steel cable, rope and metal chain are conventionally used for lifting and supporting large and heavy loads. More recently, non-metallic lifting loops have displaced the more conventional type of cable. U.S. Pat. Nos. 4,210,089 and 4,232,619 to Lindahl disclose lifting loops of this type. These lifting loops comprise a core of parallel threads enclosed within a protective covering. U.S. Pat. No. 321,473 discloses a car coupling link having a wire rope core and a metal band welded over the core while U.S. Pat. Nos. 429,174 and 510,134 disclose unsheathed, metallic wire link chain. While the non-metallic loops of Lindahl have reliable lifting characteristics and adequate strength and durability, their principal disadvantage is that they have fixed predetermined length, such as 30 or 50 foot lifting loops. In using these lifting loops, if one required a 24 foot length lifting cable, the excess length would be wrapped around the object or a support beam. These unitary lifting loops accordingly lack the versatility of a lifting chain while having the major advantage of very low weight to strength ratio.
It is the principal object of this invention to provide a linked loop non-metallic chain construction which overcomes the drawbacks of the prior art.
It is another object of this invention to provide a linked loop lifting chain which possesses the advantages of the Lindahl type lifting loops but which is more versatile in use.
It is a further object of this invention to provide a method of fabricating the above type of lifting chain.